package org.apache.lucene.search;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.BitSet;
import java.util.Date;
import java.io.IOException;

import org.apache.lucene.document.DateField;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.IndexReader;

/**
 * A Filter that restricts search results to a range of time.
 *
 * <p>For this to work, documents must have been indexed with a
 * {@link DateField}.</p>
 * 
 * @deprecated Instead, use {@link RangeFilter} combined with 
 *             {@link org.apache.lucene.document.DateTools}.
 */
public class DateFilter extends Filter {
    String field;

    String start = DateField.MIN_DATE_STRING();
    String end = DateField.MAX_DATE_STRING();

    private DateFilter(String f) {
        field = f;
    }

    /**
     * Constructs a filter for field <code>f</code> matching dates
     * between <code>from</code> and <code>to</code> inclusively.
     */
    public DateFilter(String f, Date from, Date to) {
        field = f;
        start = DateField.dateToString(from);
        end = DateField.dateToString(to);
    }

    /**
     * Constructs a filter for field <code>f</code> matching times
     * between <code>from</code> and <code>to</code> inclusively.
     */
    public DateFilter(String f, long from, long to) {
        field = f;
        start = DateField.timeToString(from);
        end = DateField.timeToString(to);
    }

    /**
     * Constructs a filter for field <code>f</code> matching
     * dates on or before before <code>date</code>.
     */
    public static DateFilter Before(String field, Date date) {
        DateFilter result = new DateFilter(field);
        result.end = DateField.dateToString(date);
        return result;
    }

    /**
     * Constructs a filter for field <code>f</code> matching times
     * on or before <code>time</code>.
     */
    public static DateFilter Before(String field, long time) {
        DateFilter result = new DateFilter(field);
        result.end = DateField.timeToString(time);
        return result;
    }

    /**
     * Constructs a filter for field <code>f</code> matching
     * dates on or after <code>date</code>.
     */
    public static DateFilter After(String field, Date date) {
        DateFilter result = new DateFilter(field);
        result.start = DateField.dateToString(date);
        return result;
    }

    /**
     * Constructs a filter for field <code>f</code> matching
     * times on or after <code>time</code>.
     */
    public static DateFilter After(String field, long time) {
        DateFilter result = new DateFilter(field);
        result.start = DateField.timeToString(time);
        return result;
    }

    /**
     * Returns a BitSet with true for documents which should be
     * permitted in search results, and false for those that should
     * not.
     */
    public BitSet bits(IndexReader reader) throws IOException {
        BitSet bits = new BitSet(reader.maxDoc());
        TermEnum enumerator = reader.terms(new Term(field, start));
        TermDocs termDocs = reader.termDocs();
        if (enumerator.term() == null) {
            return bits;
        }

        try {
            Term stop = new Term(field, end);
            while (enumerator.term().compareTo(stop) <= 0) {
                termDocs.seek(enumerator.term());
                while (termDocs.next()) {
                    bits.set(termDocs.doc());
                }
                if (!enumerator.next()) {
                    break;
                }
            }
        } finally {
            enumerator.close();
            termDocs.close();
        }
        return bits;
    }

    public String toString() {
        StringBuffer buffer = new StringBuffer();
        buffer.append(field);
        buffer.append(":");
        buffer.append(DateField.stringToDate(start).toString());
        buffer.append("-");
        buffer.append(DateField.stringToDate(end).toString());
        return buffer.toString();
    }
}
